Dismantling the older AI lenses varies upon the version of lens, model of lens, revision of of that lens, and what portion is having problems. I will give you a big big warning if you dismantle the helicoil assembly (also known as the focusing assembly) re-threading them back together is not always an easy task. Also keep in mind if you reassemble them at the wrong point the lens will not focus correctly. I have had a lot of luck with stiff focusing lenses simply putting some what I cam going to call turbine oil (not a lot) on the helicoils and then bringing the lens through the focusing range a whole lot which then works the oil into the threading has worked for me in the past. Doing some google searching may find some tear downs or advice on how to properly dismantle the lens.

** I do not claim to be an expert on this but have had a lot of very good luck cleaning/repairing the glass that I have gotten hold of in the last few years.**

As others have stated above if you are not familiar with dismantling/cleaning/repairing lenses there are lots of very reputable places to bring the lens/ship the lens to be serviced.

framer said:
Once done it's good for another 30+years. If you like the lens get it done right. KEH does a good job if you need a source.

Framer is correct. Get it done right and those older AI lenses will last (almost) forever.

So long as you can handle manual focus and know something about exposure so you can set the aperture yourself (something that many find too hard to learn how to do these days), then they are not too hard to work on ... but its NOT really a do it yourself project.

I've had several old lenses clean and relubed. An AI lens does not cost that much to have it cleaned. They use a special grease. Once done it's good for another 30+years. If you like the lens get it done right. KEH does a good job if you need a source.

Getting it apart may not be the problem... putting it back together could be more than one can handle with just simple directions. Here is someone who can advise you, a Leica specialist but one who can rebuild a Nikon lens I am certain. However, he may suggest a used one from eBay instead of rebuilding...

I have a 50mm f/1.4 AI on my hands here, and the focus ring seriously needs a regrease. It is dry as. The optics aren't particularly good, so I don't care about it enough to take it to a professional service place. I am having trouble getting it open, all I can do is get the lens mount off, and partly disconnect the aperture dial, but it never comes off all the way. Does anyone know much about this?